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In this paper, a comparison between different configurations of surface plasmon resonance (SPR) biosensors has been theoretically conducted to improve the performance of the designed biosensor. The proposed biosensor configurations contain zirconium nitride (ZrN) as an alternative plasmonic material, which comprises different perovskite materials (KNbO3, LiTaO3, LiNbO3, SrTiO3, and BaTiO3) in the visible region. Depending on the study calculations, the reflection spectra of the suggested designs were studied under the angular interrogation mode based on Fresnel coefficients for the transverse magnetic polarized light. The numerical findings demonstrated that the SPR biosensor, which has the configuration of [Prism/BaTiO3/ZrN/BaTiO3/Biosensing medium], represents the best biosensor due to its higher sensitivity and minimum reflectivity values. Meanwhile, sensitivity could receive 179.58 (deg/RIU). Therefore, it is believed that the proposed SPR biosensor designs could be promising through wide-ranging applications, specifically in biomedical, chemical, and environmental protection. [ABSTRACT FROM AUTHOR]

In this study, the transfer matrix method is used to analyze the optical properties of a layered structure, {Air(SrTiO3/BSCCO)20Substrate}, consisting of air, SrTiO3, BSCCO (bismuth strontium calcium copper oxide) bilayers, and a substrate. This paper aims to investigate the transmittance spectra of two proposed one-dimensional (1D) structures, including a conventional superconductor photonic crystal (PC) and a gyroidal superconductor PC at infrared (IR) wavelengths. A comprehensive analysis has been carried out to provide useful insights into the optical properties and the behavior of the proposed structure, highlighting the impact of many parameters, such as refractive index, filling fraction, and layer thickness. The numerical findings showed that the permittivity of the BSCCO superconductor of a gyroidal geometry takes a different response compared to the conventional one. Notably, the filling fraction and refractive index of the host material have a significant control on both real and imaginary parts of the gyroidal BSCCO permittivity through the considered wavelengths. Thus, the proposed design provides high transmittivity outside the obtained photonic band gap compared to the conventional one. We believe that the designed one-dimensional gyroidal BSCCO photonic crystals could act as an efficient reflector through near IR for optoelectronics and energy applications. [ABSTRACT FROM AUTHOR]

The present study intends to solve the problem of low-temperature sensitivity of most conventional period materials. A solid/solid one-dimensional phononic crystal design is proposed as a pragmatic thermal sensor. Here, each unit cell of the proposed phononic crystal sensor is designed from epoxy and concrete. In this structure, irregularity in layers' arrangement results in the generation of resonant peaks at the transmission spectrum. The irregularity is introduced to the system by stacking two mirror phononic crystals to form a whole symmetric phononic crystal design. Thermal variations lead to significant changes in Young's modulus of concrete and epoxy; consequently, transmission spectra and local resonant peaks are shifted as well. Firstly, the band gap changes, and sensor performance were investigated under different conditions such as the incident angle and the number of unit cells to get the optimum parameters. Meanwhile, promising results have been obtained, with increasing the incident angle, the sensitivity increases exponentially till it reaches 1.5 × 103 Hz/°C at an incident angle = 18°. Also, with increasing the temperature from 25 to 100 °C, the sensitivity increases dramatically from 188.8 to 362.4 Hz/°C, respectively. In addition, the largest value of Q-factor was investigated at periodicity number = 4. Moreover, in this regard, the Q-factor has the value of 3708 at 25 °C and it reaches to the value of 896.6 at 100 °C. That is to say, the obtained results may be useful in designing thermal sensors with a high sensitivity value. [ABSTRACT FROM AUTHOR]

Resonant acoustic band gap materials have steered a new sensing technology era. This study is presented to investigate of the one-dimensional (1D) phononic crystals (PnCs), involving periodic, as well as quasi-periodic 1D layered PnCs represented as a highly sensitive biosensor to detect and monitor the quality of milk. In this regard, the numerical findings show that the examined periodic PnCs structure outperformed the quasi-periodic structure. In particular, it provides a wider phononic band gap and greater sensitivity as well. In addition, the quasi-periodic design (especially Fibonacci sequence S4) introduces multiple resonance peaks via transmission spectra, which may lead to some conflicts during the detection process. The findings reveal that the frequency of the resonant peak can effectively change with varied milk solution concentrations and temperatures. The optimized sensor is capable of differentiating between concentrations ranging between 0 and 50 % with a 10 % step, and it can also differentiate between temperatures, which range between 5 °C and 50 °C. This makes it ideal for precise detection of other liquids and solutions. The sensor performs efficiently for all milk solution concentrations. Here, the findings demonstrated that the examined defective PnC structure exhibited the most favorable sensitivity of the value of 94.34 MHz, so it showed the highest sensitivity when varying milk concentrations. In addition, the configurated sensor provided high QF and FOM values of 3,853.645161 and 157.42, respectively. On the other hand, the sensor performs very well for all temperatures of the milk solution. As such, the S4 quasi-periodic structure is characterized as the optimal sensor structure when varying temperatures, introducing a sensitivity of 4.78 MHz/°C, QF of 4,278.521, and FOM of 7.48 °C−1. [ABSTRACT FROM AUTHOR]